Thirty male rats were used. Behavioral changes were examined in the morning of the 21th, 23th, and 25th exposure day.
Rats anxiety-related behaviors were examined in the open field test, elevated plus maze, and the light/dark box during five minutes observations. The open field was a black circular area (diameter: 160 cm, height: 50 cm) with two concentric circles lines on the floor. The elevated plus maze consisted of two opposite open arms, an open platform in the center, and two opposite closed arms. To avoid fear rats tend to stay close to the sidewall in the open field and to the closed arms in the elevated plus maze. Grooming is interpreted as a stress coping and de-arousal behavior response to increased anxiety level due to novel environment situations in the tests. The light/dark box was constructed from two equally sized boxes which were connected by an opening. In the dark box, there was no appreciable illumination. The light box was white and provided illumination at a level of 100 lux.
Exposure duration: 1 h/day or 4 h/day for 25 days
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The magnetic field exposure for 4 hours/day increased the anxiety-like behaviors in rats in the open field test and the elevated plus maze test (increased time spent in outer ring than in central ring, increased grooming; reduced time spent in open arms and central part and increased time spent in closed arms). No effect was observed in the light/dark box test. Moreover, magnetic field exposure for 1hour/day had no effect in any test.
These findings suggest that the exposure to chronic extremely low frequency magnetic field has anxiogenic effect in rats, which is dependent on the daily exposure duration and which is more sensitive to void space than to strong light.